1. Field of the Invention
The invention relates generally to an apparatus to be used in any fluid medium for responding to an increasing and then decreasing pressure and, in particular, for assisting in the deployment of a horizontal acoustic line array in the medium.
2. Description of the Prior Art
Sonobuoys are well known in the prior art. For example, U.S. Pat. No. 4,189,786 describes a radio buoy assembly including an intelligence capsule. Such sonobuoys have been generally configured to deploy vertical acoustic line arrays of sensors for monitoring. Recently, a need for sonobuoys which deploy horizontally spaced arrays of hydrophones, such as that disclosed in U.S. Pat. No. 4,254,480, has developed. Horizontal line arrays are deployed vertically in the ocean and then horizontally positioned by the drag force on the array due to water currents. A float at the end of the line array aids in the positioning. A weighted element at the forward end of the line array provides a pivot point about which the array rotates at the desird depth. The line array is neutrally buoyant and has a sea chute at its end for stabilizing its horizontal position.
In practice, the line array positions itself horizontally very slowly. This is a major drawback in the use of horizontal line arrays. A sea chute will further impede the attainment of the horizontal position of the line array because it resists the motion of the line array through the ocean. Therefore, it is desirable to keep the sea chute collapsed until the horizontal position is reached. The float, on the other hand, needs to be discarded when the horizontal position is reached or the line array will continue to rise.
A simple, inexpensive method is needed to perform these dual functions. A single action pressure release cannot deploy the chute and release the float because the apparatus would release during the vertical deployment cycle when the apparatus first passes the pressure at which horizontal stability occurs. Because of this, the release of the float and the deployment of the sea chute had to be done with a double action device connected to a containment bag which held the sea chute and the float.